1. Field of the Invention
Known superconducting electronic devices are based on the properties of a weak link (or Josephson junction) between two bodies of superconducting material. Such a weak link may be formed using (i) a point contact, (ii) a microbridge, or (iii) a thin insulating barrier between the superconducting bodies.
2. Description of Related Art
The recently discovered ceramic superconductors offer advantages compared with conventional superconductors in that they become superconducting at more easily accessible temperatures. These materials are difficult to handle for several reasons and, in particular, require high processing temperatures which are incompatible with conventional microfabrication technology (such as photolithography).
However the ceramic superconductors form naturally into a granular structure in which the boundaries between the grains act as natural weak links. These natural weak links have already been exploited in the demonstration of SQUID-like behaviour. In this demonstration the superconducting circuit is formed from random loops of interconnected grains within a ceramic specimen in which the grain boundaries have the appropriate weak link behaviour.